Final answer:
The enzymatic method is the most commonly used method for bilirubin analysis, due to its specificity, simplicity, and ability to provide quick and accurate measurement of bilirubin levels.
Step-by-step explanation:
The most commonly used method for bilirubin analysis is the enzymatic method. Although high-performance liquid chromatography (HPLC) and mass spectrometry are widely used in bioanalytical assays for drug testing and other analyses, the enzymatic method is preferred for bilirubin due to its specificity and simplicity. Historically, Van Den Bergh reactions, including direct and indirect tests, have been used for the qualitative assessment of conjugated and unconjugated bilirubin. However, today, automated enzymatic methods, which involve the conversion of bilirubin to a colored product that can be measured photometrically, are more prevalent. This enzymatic approach allows for quick and reliable measurement of total and direct bilirubin levels in blood samples, which is critical for diagnosing and monitoring jaundice and other liver-related conditions.